Before you scald my ears off, I'm not an idiot that fills up with regular to save 10 cents a litre (I'm Canadjian). I did happen to run very low on gas on a remote highway at night and the only place open didn't have 91 octane fuel. It was either go with a touch of regular to make it to the next city or get stranded. Will this do any long term damage to the engine?

 

no i dont think so, i've put once or twice 89 but after that never, always 91.

 

NO..but don't do it again...the engine is not designed to run regular...but it can adapt in situations like you described.

 

NO. But you give up some ponies.

 

You can fill up with regular all the time if you like, there is no detriment to the engine. One thing you may notice is engine knocking though, that will drive you crazy, so you will likely not want to put anything other than premium in your engine.

The only real detriment is the loss of power you may notice, but if yo are just running around town or highway cruising and don't need the high performance from your engine, the lower octane fuel will work.

 

Engine knocking is a lot more than noise that will annoy you. Over time knocking or pinging can do damage.

 

No it does not hurt the engine. The computer will compensate for the lower octane and it will not knock. However, you will see diminished horsepower and milage.

Car and Driver did a study of this a year or so ago and found that cars designed to take higher octane get better milage with the higer octane and this generally ofsets the increased cost of the gas. So you save no money getting regular gas, but it will not hurt your car either.

 

The engine should not knock. If it does somethiong is wrong with the fuel system sensors. The fuel system computer will retard timing to avoid any knocking. As stated before a knock here or there will not harm an engine, constant knocking on the other hand will.

 

Here is a scientific anser to your question.

http://www.caranddriver.com/article....&page_number=1

 

nice find. now i feel like iam not waisting money at the pump.

 

And for those of you too lazy, or technically challenged, to read the entire link, here are the pertinent excerpts which apply to our TL’s.

This one doesn’t fully apply, since the factory already recommends the most expensive fuel. The only exception is that the factory recommends 91 octane, and higher octanes are available in most areas. In my area, there is no price increase for 93 octane compared to prices for 91 octane.


This is the one that really applies to our TL. There is always the possibility of damage fron engine knock if the knock sensor doesn’t always do its job. And, most importantly, the performance decrease may cause you problems when you try to pass a car and the knock sensors limit the engine revs to 4,000 (based on actual testing and experience).

 

If you can audibly detect engine knock there is no doubt that engine damage is occuring at every single audible knock event.

I've detected detonation several times on my new '04 Tl using 93 octane on a hot and humid day WOT in the upper range of the rev band under load. The odds are that the knock sensor is disabled in the higher rev band as it is with many modern vehicle to avoid false positives from engine noise. The knock events that are detected by the sensor don't limit the revs 4k but will trim down the timing advance in that range of the rev band.

 

Is this true? I have a hard time believing that manufacturers would disable the knock sensor when the motor is under the most load and most likely to sustain damage from any detonation that did occur.

Knock sensors listen for very specific frequencies and I can't believe that if the knock sensor on my clickety-clackety roller cam Buick doesn't false, the knock sensor on a modern honda motor would.

Can you give an example of a car that you know has code that disables the knock sensor above some given rpm?

-Scott

 

When I tried one tank of 87 octane as a test, I soon found that the engine would NOT rev above 4,000 rpm. The MIL light flashed, and the rev limiter kicked in. Also, if you were going over 4,000 rpm and tried to downshift with SS, it wouldn't let you.

As soon as I got the tank low enough, I filled up with 91 octane, and then everything worked as it should.

 

If you can't afford to drive the damn car you shouldn't own it





cheapass

 

Say you save $0.20/gal so every fill you'll save about $2-$3. Say you fill once a week that is 52 times a year and $104-$156 so for a life of car say 10 years if you own and 4-5 years if you lease, you'll save $750-$1500. Is it worth?

 

if u use 87 and its 52 tanks a year, then if u would use 91 it would be less b/c the engine will use less gas.